this is from the second season JLA episode "Maid of Honor". Bruce Wayne meets Princess Diana of Themyscira for the first time (ha!) and saves her from paparazzi by asking her to dance. this goes better for either of them than they would have thought.
now some fans say Diana didn't figure out who Bruce was til the middle of the episode, but I don't think he's fooled her at all. she's got the wisdom of Athena, after all! I wish this relationship would have been explored a bit more in the series though. who's gonna say no to Wonder Woman for long? not even Batman!